Question

a stratigraphic column shows (from bottom to top): layer d (basalt), layer c (sandstone), layer b (shale), layer a (limestone). no folding or faulting is present. which statement uses a law? the youngest layer is always igneous, so d must be the most recent deposit in every rock column. in undisturbed sedimentary sequences, older layers are below younger layers, so c is older than a. fossils must be distributed evenly in all layers, so each layer will have the exact same species. the order of layers changes randomly each year, so age can only be known by guessing.

Explanation:

The correct statement relies on the Law of Superposition, a key geological principle stating that in undisturbed sedimentary rock sequences, older layers lie beneath younger layers. The other options contain incorrect claims: igneous layers are not always the youngest, fossils are not evenly distributed with identical species in all layers, and layer order does not change randomly in undisturbed sequences.

Answer:

B. In undisturbed sedimentary sequences, older layers are below younger layers, so C is older than A.